There cannot any one moral rule be proposed whereof a man may not justly demand a reason.
John LockeUnderstanding like the eye; whilst it makes us see and perceive all things, takes no notice of itself; and it requires art and pains to set it at a distance and make it its own subject.
John LockeYou shall find, that there cannot be a greater spur to the attaining what you would have the eldest learn, and know himself, than to set him upon teaching it his younger brothers and sisters.
John LockeThus the law of nature stands as an eternal rule to all men, legislators as well as others. The rules that they make for other mens actions, must, as well as their own and other mens actions, be conformable to the law of nature, i.e. to the will of God, of which that is a declaration, and the fundamental law of nature being the preservation of mankind, no human sanction can be good, or valid against it.
John Locke